Settings > All Settings
Expand Settings > Notification Server > Site Server Settings > Task Service > Settings, right-click Task Service Settings, Clone, provide a name, delete target, assign to Notification Server only, set to respond to maximum of 100 clients using drop-down. Save changes and enable policy. Finally, modify other Task Service Settings to exclude Notification Server but otherwise include all site servers running task service.
But I'm hoping Andrew can confirm what I was told by backline support. I've been using that method without any noticed bad things for months.